JP7368112B2 - Motor current value detection device - Google Patents

Description

The present invention relates to a motor current value detection device.

A known technique is to amplify the voltage across a shunt resistor caused by current flowing through the shunt resistor using an operational amplifier, and then perform A/D (analog/digital) conversion to detect the value of the current.

JP2017-79515A

Operational amplifiers generally have a slight input offset voltage, and some have negative input offset voltages (values less than 0) due to individual differences. A slight input offset voltage itself is often not a real problem, but if the input offset voltage is negative, the rise of the amplifier's output voltage is delayed with respect to the rise of the current, which may deteriorate detection accuracy. There is.

The present invention has been made in view of these points, and an object of the present invention is to provide a motor current value detection device that can reduce the delay in the rise of the output voltage of the amplifier with respect to the rise of the current.

In one aspect, an amplifier electrically connected across a resistor through which a current to be detected flows;
an A/D converter that is electrically connected to the output side of the amplifier and converts the output of the amplifier into A/D and outputs the A/D converter;
an offset correction unit that performs offset correction processing to correct an input offset correction voltage of the amplifier when the input of the amplifier is less than 0 in a non-energized state where the current to be detected is not flowing;
A motor current value detection device is provided.

According to the present invention, it is possible to provide a motor current value detection device that can reduce the delay in the rise of the output voltage of the amplifier with respect to the rise of the current.

1 is a diagram showing an example of a schematic configuration of an electric oil pump 1 to which a motor current value detection device of the present invention is applicable. 3 is a diagram showing a schematic configuration of a drive device 8. FIG. 5 is a diagram showing various waveforms when the input offset voltage of the operational amplifier 121 is on the plus side. FIG. 5 is a diagram showing various time-series waveforms when the input offset voltage of the operational amplifier 121 is on the negative side. FIG. FIG. 3 is an explanatory diagram of a method of correcting a setting value of an offset correction register. FIG. 3 is an explanatory diagram of an example of a method of searching for a correction target value of an offset correction register. 3 is a schematic flowchart showing an example of the operation of the offset correction section 130.

Hereinafter, each embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Here, first, prior to explaining the motor current value detection device of the present invention, an electric oil pump to which the motor current value detection device of the present invention is applicable will be explained.

FIG. 1 is a diagram showing an example of a schematic configuration of an electric oil pump 1 to which a motor current value detection device of the present invention is applicable. The motor current value detection device of the present invention is preferably applied to the electric oil pump 1, but can be applied to any other electronic device that requires detection of a current value.

The electric oil pump 1 is used, for example, as a hydraulic pressure supply source that supplies oil to an oil supply destination T such as a hydraulic device such as a continuously variable transmission mounted on a vehicle.

The electric oil pump 1 is connected to an ECU (Electronic Control Unit) 2. The electric oil pump 1 pumps up oil stored in an oil pan 3, applies hydraulic pressure, and supplies the oil to an oil supply destination T.

ECU 2 is connected to electric oil pump 1 and temperature sensor 4 . Further, the ECU 2 is connected to various electronic components (other ECUs, various sensors, etc.) in the vehicle via an appropriate bus (not shown) such as a CAN (Controller Area Network). The ECU 2 drives the electric oil pump 1 in order to supply oil to the oil supply destination T when the engine is stopped due to an engine stop or the like. For example, when the engine is stopped, the ECU 2 sends a drive command including a target value of the phase current to the motor (hereinafter referred to as "target phase current value") according to the temperature of the oil measured by the temperature sensor 4. Send to oil pump 1.
The electric oil pump 1 includes an oil pump 5, a motor 6, a rotation angle detection section 7, and a drive device 8.

The oil pump 5 is connected to the motor 6 and the oil supply destination T. The oil pump 5 is a pump driven by a motor 6. The oil pump 5 is driven by a motor 6 to pump oil in the oil pan 3 to an oil supply destination T.

The motor 6 includes a rotor having permanent magnets, and a stator in which coils Lu, Lv, and Lw corresponding to three phases (U, V, and W) are wound in order in the rotational direction of the rotor. Each of the coils Lu, Lv, and Lw of each phase is connected to a drive device 8. For example, motor 6 is a brushless motor.

The rotation angle detection section 7 detects the rotation angle of the motor 6. Then, the rotation angle detection section 7 outputs an output signal corresponding to the detected rotation angle to the drive device 8.

The drive device 8 is connected to the ECU 2 and the motor 6. The drive device 8 controls the drive of the motor 6 based on a drive command output from the ECU 2. For example, the drive device 8 performs feedback control so that the phase current of the motor 6 becomes the phase current target value included in the drive command input from the ECU 2. Further, the drive device 8 performs magnetic flux weakening control to increase the motor torque when the motor 6 rotates at high rotation speed, and performs advance angle control to advance the timing of energizing the motor 6 to the advance side.

FIG. 2 is a diagram showing a schematic configuration of the drive device 8. As shown in FIG.

As shown in FIG. 2, the drive device 8 includes a power supply section 9, an inverter 10, a shunt resistor 11, and a microcomputer 12 (hereinafter referred to as "microcomputer 12").

The power supply unit 9 is, for example, a battery mounted on a vehicle. The power supply section 9 may be a secondary battery such as a nickel metal hydride battery or a lithium ion battery. Moreover, an electric double layer capacitor (capacitor) can also be used instead of a secondary battery.

The inverter 10 includes a plurality of switching elements SW, and converts a power supply current into a phase current by controlling the ON and OFF states of the switching elements using PWM (Pulse Width Modulation). Specifically, inverter 10 has six switching elements SW1 to SW6. Inverter 10 converts power supply current into phase current by switching switching elements SW1 to SW6 on and off.

The switching elements SW1 and SW4 connected in series, the switching elements SW2 and SW5 connected in series, and the switching elements SW3 and SW6 connected in series are connected to the high potential side of the power supply section 9 and the ground potential. are connected in parallel between.

Further, a connection point between the switching element SW1 and the switching element SW4 is connected to one end of the coil Lu. A connection point between switching element SW2 and switching element SW5 is connected to one end of coil Lv. A connection point between switching element SW3 and switching element SW6 is connected to one end of coil Lw.

In this embodiment, a case will be described in which the switching element SW is an n-type channel FET (Field Effect Transistor), but the present invention is not limited to this. Transistor) It may be. Each switching element SW1 to SW6 has a configuration in which it is connected in parallel with a free wheeling diode D1 to D6. Furthermore, gate terminals of each of the switching elements SW1 to SW6 are connected to the microcomputer 12.

Shunt resistor 11 is provided between the low potential side of inverter 10 and ground. Note that in a modification, the shunt resistor 11 may be provided between the high potential side of the inverter 10 and the power supply section 9. The shunt resistor 11 forms an element of a current sensor for detecting phase currents.

The microcomputer 12 forms a motor current value detection device. As shown in FIG. 2, the microcomputer 12 includes a motor control section 120, an operational amplifier 121, an A/D converter 122, a current value acquisition section 124, and an offset correction section 130. The motor control unit 120, the current value acquisition unit 124, and the offset correction unit 130 are configured such that, for example, a CPU (Central Processing Unit) (not shown) of the microcomputer 12 is connected to a storage device such as a ROM (Read Only Memory) of the microcomputer 12. This can be achieved by executing a program in (not shown).

The motor control unit 120 controls the motor 6 by controlling the drive of the inverter 10 in response to a drive command from the ECU 2 . At this time, as described above, the motor control unit 120 controls the switching elements of the inverter 10 based on the phase current information from the current value acquisition unit 124 so that the phase current in the phase current information matches the phase current target value. A gate signal is applied to each gate electrode of SW1 to switching element SW6. Note that the details of the method of controlling the motor 6 are arbitrary.

The operational amplifier 121 includes a non-inverting input terminal, an inverting input terminal, and one output terminal, and is also called an operational amplifier. The operational amplifier 121 has a non-inverting input terminal electrically connected to the high potential side of the shunt resistor 11, an inverting input terminal electrically connected to the low potential side of the shunt resistor 11, and an output terminal connected to the A/D converter 122. electrically connected. The operational amplifier 121 forms one element of a current sensor for detecting phase currents.

The operational amplifier 121 amplifies the voltage difference occurring across the shunt resistor 11 and outputs it to the A/D converter 122. Specifically, the operational amplifier 121 configures a differential input circuit in cooperation with four resistors R1 to R4. In this case, for example, if R1=R3, R2=R4, the potential on the high potential side of the shunt resistor 11 is V2, and the potential on the low potential side of the shunt resistor 11 is V1, the output voltage V0 of the operational amplifier 121 is V0. =R2/R1(V2-V1).

The A/D converter 122 converts the output (analog signal) from the operational amplifier 121 into a digital signal and outputs it to the current value acquisition section 124. The A/D converter 122 samples the output from the operational amplifier 121 after a predetermined time ΔT2 has elapsed from the rising edge of the PWM signal (rising edge of the on-duty). That is, the timing of A/D conversion is a predetermined time ΔT2 after the rising edge of the PWM signal. The predetermined time ΔT2 is, for example, fixed, and is significantly shorter than the minimum possible value of the on-duty period of the PWM signal.

The current value acquisition unit 124 calculates the phase current based on the output signal from the A/D converter 122, and generates phase current information.

The offset correction unit 130 performs offset correction to compensate for the offset of the output voltage of the operational amplifier 121 caused by the input offset voltage of the operational amplifier 121. Note that the function of the offset correction section 130 can be realized by using, for example, an AMP input offset correction function provided in the existing microcomputer 12.

The input offset voltage refers to an error voltage possessed by an operational amplifier that constitutes a differential input circuit, and in an ideal operational amplifier, the input offset voltage is 0V (that is, "no offset"). However, in general, actual operational amplifiers (operational amplifiers that meet standard values) often have a slight input offset voltage, and the value of the input offset voltage can change due to aging, temperature changes, and the like. Note that normally, in an operational amplifier for detecting phase current (for example, operational amplifier 121), if the input offset voltage is to a certain extent, it is necessary not to use phase current information below a predetermined value and to appropriately set the timing of A/D conversion. etc., it is possible to prevent the accuracy of the phase current information from being affected, and there is no substantial problem.

However, in recent years, there has been a growing desire to set the controllable range (variable range of duty) as wide as possible.

Here, the standard value for the input offset voltage is usually expressed as an absolute value, and the input offset voltage has a positive side (+ polarity) and a negative side (- polarity). In the case of an operational amplifier where the input offset voltage is on the negative side (a value less than 0), an event in which the rise of the operational amplifier's output voltage is delayed (hereinafter referred to as a "rise delay event") occurs, resulting in poor detection accuracy. There is. The rise delay event will be explained with reference to FIGS. 3 and 4.

FIG. 3 is a diagram showing various waveforms when the input offset voltage of the operational amplifier 121 is on the positive side, and FIG. 4 is a diagram showing various time series waveforms when the input offset voltage of the operational amplifier 121 is on the negative side. be. 3 and 4, from the top, the time series waveform of the PWM signal, the time series waveform of the input voltage of the operational amplifier 121 (indicated as "AMP input voltage" in FIGS. 3 and 4), and the output voltage of the operational amplifier 121, respectively. A time-series waveform (denoted as "AMP output voltage" in FIGS. 3 and 4) is shown.

The time series waveform of the PWM signal represents the on/off state of the PWM signal, ΔT10 represents the on-duty period, and ΔT11 represents the off-duty period. Note that in FIG. 3, the on-duty period ΔT10 is longer than the off-duty period ΔT11, but the rise delay event occurs even when the on-duty period ΔT10 is relatively long.

The time-series waveform of the input voltage of the operational amplifier 121 also shows a 0V line. In FIG. 3, the input voltage of the operational amplifier 121 during the off-duty period of the PWM signal is slightly greater than 0V, whereas in FIG. 4, the input voltage of the operational amplifier 121 during the off-duty period of the PWM signal is slightly greater than 0V. small. Note that such a "deviation" from 0V occurs due to the above-mentioned input offset voltage.

As shown in FIGS. 3 and 4, the output voltage of the operational amplifier 121 rises in response to the rise of the input voltage of the operational amplifier 121 (see, for example, time t1 and time t1') in response to the rise of the PWM signal (see, for example, time t0). , falls in response to the fall of the input voltage of the operational amplifier 121 in response to the fall of the PWM signal, but a delay time ΔT1 occurs at the time of rise. This delay time ΔT1 is not significant when the input offset voltage is on the plus side, as shown in FIG. 3, but becomes significant when the input offset voltage is on the minus side, as shown in FIG. 4. This is because the operational amplifier is inactive when the input voltage is negative and is activated only when the input voltage becomes positive. That is, when the input offset voltage is on the negative side, startup is delayed by a small amount of time until the input voltage becomes positive, and the delay time ΔT1 tends to become longer by that amount.

When such a delay time ΔT1 becomes longer, the timing of A/D conversion by the A/D converter 122 (time t2, see arrow R1) arrives before the output voltage of the operational amplifier 121 rises sufficiently, and the A/D converter 122 The output value becomes significantly lower than the expected value (denoted as "Vn" in FIGS. 3 and 4). As a result, the value of the phase current calculated by the current value acquisition unit 124 becomes lower than the expected value (that is, the value that should be obtained from Vn).

In this way, when the input offset voltage of the operational amplifier 121 is on the negative side, the rise of the output voltage of the operational amplifier 121 is delayed, which may deteriorate phase current detection accuracy. This problem does not occur when the input offset voltage of the operational amplifier 121 is on the positive side (see FIG. 3).

Note that as a measure to suppress such deterioration in phase current detection accuracy, there is a method of delaying the timing of A/D conversion by the A/D converter 122. However, in this method, due to the necessity of setting the timing of A/D conversion by the A/D converter 122 during the on-duty period ΔT10, it is necessary to increase the lower limit value of the variable range of the on-duty period ΔT10. Gender arises. This means narrowing the duty variable range (ie, controllable range).

In addition, the input offset voltage of the operational amplifier 121 can be compensated by the input offset correction voltage of the operational amplifier 121, but depending on the set value of the input offset correction voltage, a state in which no phase current flows (hereinafter also referred to as a "non-energized state") In some cases, the input voltage of the operational amplifier 121 is less than 0 (i.e., on the negative side), and in this case, the above-mentioned problem (the rise of the output voltage of the operational amplifier 121 is delayed, resulting in poor phase current detection accuracy) occurs.

In view of this, in the present embodiment, the offset correction unit 130 performs offset correction when the input voltage of the operational amplifier 121 is less than 0 (i.e., on the negative side) in a non-energized state, as described below. This makes it possible to suppress deterioration in phase current detection accuracy without unnecessarily narrowing the controllable region.

Specifically, by utilizing the fact that the positive/negative of the input voltage of the operational amplifier 121 in the non-energized state can be determined based on the positive/negative of the output voltage of the operational amplifier 121 in the non-energized state, the offset correction unit 130 When the output voltage of the operational amplifier 121 is on the negative side, the set value (an example of an adjustment parameter) of the offset correction register is corrected so that the output voltage of the operational amplifier 121 in the non-energized state becomes on the positive side. The set value of the offset correction register has a function of setting the input offset correction voltage of the operational amplifier 121 (a function of changing the input offset correction voltage of the operational amplifier 121). That is, the input offset correction voltage is an input (input to the operational amplifier 121) for changing the input offset voltage of the operational amplifier 121, and the set value of the offset correction register is a value that determines the input offset correction voltage.

FIG. 5 is an explanatory diagram of a method of correcting the set value of the offset correction register. In FIG. 5, the horizontal axis represents the setting value of the offset correction register, the vertical axis represents the output value of the A/D converter 122 (denoted as "AD detection value" in FIG. 5), and the setting value of the offset correction register is expressed as follows. The manner in which the output value of the A/D converter 122 changes when it is decremented by "1" from the maximum value on the plus side (denoted as "+ side MAX" in FIG. 5) is shown.

Here, the characteristics shown in FIG. 5 are characteristics in a non-energized state. The output value of the A/D converter 122 in the non-energized state represents the output voltage of the operational amplifier 121 in the non-energized state. Therefore, if the output voltage of the operational amplifier 121 in the non-energized state changes across positive and negative levels, the output value of the A/D converter 122 in the non-energized state changes across positive and negative levels.

In the case of the operational amplifier 121 in FIG. 5, when the setting value of the offset correction register is corrected to a value obtained by subtracting "4" from the maximum value on the plus side (denoted as "+ side MAX-4" in FIG. 5), the A/D converter 121 The output value of the A/D converter 122 is on the positive side closest to 0V with respect to the ideal value of 0V (that is, the output value of the A/D converter 122 slightly exceeds 0). In addition, when the setting value of the offset correction register is corrected to the value obtained by subtracting "5" from the maximum value on the positive side (denoted as "+ side MAX-5" in FIG. 5), the output voltage of the operational amplifier 121 becomes the closest value to 0V. This is on the negative side (that is, the output value of the A/D converter 122 is slightly less than 0). Therefore, in the case of this operational amplifier 121, the offset correction unit 130 corrects the set value of the offset correction register to a value obtained by subtracting "4" from the maximum value on the positive side (indicated as "+ side MAX-4" in FIG. 5). do.

Note that the characteristics shown in FIG. 5 relate to a certain individual operational amplifier 121, and may have different characteristics for other individual operational amplifiers 121. Therefore, the offset correction unit 130 searches for the value of the offset correction register for each operational amplifier 121 such that the output value of the A/D converter 122 in the non-energized state is on the positive side closest to 0V. Hereinafter, the value of the offset correction register (an example of a first value) that causes the output value of the A/D converter 122 to be on the positive side closest to 0V will be simply referred to as "correction target value of the offset correction register."

Such a search for the correction target value of the offset correction register is performed in a non-energized state. The method of searching for the correction target value of the offset correction register is arbitrary, but preferably includes changing the value of the offset correction register so that the output value of the A/D converter 122 crosses 0V. In this case, when the output value of the A/D converter 122 crosses 0V and becomes a positive side, the value of the offset correction register at that time or the output value of the A/D converter 122 crosses 0V and becomes a negative side. When this happens, the value of the offset correction register immediately before that becomes the "correction target value of the offset correction register."

FIG. 6 is an explanatory diagram of an example of a method of searching for a correction target value of an offset correction register. In FIG. 6, the horizontal axis represents time, the vertical axis represents the output value of the A/D converter 122 (denoted as "AD detection value" in FIG. 6), and while changing the value of the offset correction register, A mode in which a corrected target value of is searched for is schematically shown.

In the case of the operational amplifier 121 in FIG. 6, at time t59, the set value of the offset correction register is a positive value, and the output value of the A/D converter 122 is significantly larger than 0V. Therefore, the offset correction unit 130 once changes the set value of the offset correction register to the minimum value (denoted as "-side MIN" in FIG. 6) at time t60. In this case, the output value of A/D converter 122 is significantly smaller than 0V. Then, at time t61 after time t60, the offset correction unit 130 changes the set value of the offset correction register to a value incremented by "1" from the minimum value (denoted as "-side MIN+1" in FIG. 6). do. In this case, the output value of A/D converter 122 remains significantly smaller than 0V. Therefore, as shown from time t62 to time t64, the offset correction unit 130 operates until the output value of the A/D converter 122 becomes larger than 0V (that is, until the output value of the A/D converter 122 crosses 0V to the positive side). ), the set value of the offset correction register is incremented by "1". In the case of the operational amplifier 121 in FIG. 6, the output value of the A/D converter 122 crosses 0V to the positive side at time t64. Therefore, in this case, a value incremented by "4" from the minimum value (denoted as "-side MIN+4" in FIG. 6) becomes the correction target value of the offset correction register.

In FIG. 6, the set value of the offset correction register is incremented by "1", but it may be incremented by "2". In addition, in FIG. 6, the setting value of the offset correction register is temporarily changed to the minimum value (denoted as "- side MIN" in FIG. 6), but the value other than the minimum value (the output of the A/D converter 122 The value may be changed to a value smaller than 0V.

In addition, in FIG. 6, the setting value of the offset correction register is first changed to the minimum value (denoted as "- side MIN" in FIG. 6), and then the setting value of the offset correction register is incremented by "1". However, the set value of the offset correction register may be decremented by "1" from the value as it is (that is, the value before correction). In this case, as described above, when the output value of the A/D converter 122 crosses 0V and becomes negative, the value of the offset correction register immediately before that value becomes the "correction target value of the offset correction register."

In this way, according to the present embodiment, the offset correction unit 130 searches for the correction target value of the offset correction register when the output voltage of the operational amplifier 121 in the non-energized state is on the negative side, and searches for the correction target value of the offset correction register. Correct the setting value of the offset correction register to the correction target value. When the setting value of the offset correction register is corrected to the correction target value of the offset correction register, the output voltage of the operational amplifier 121 in the non-energized state becomes the positive side closest to 0V. That is, the output voltage of the operational amplifier 121 in the non-energized state, which was on the negative side, is corrected to a small value on the positive side. This means that the input voltage of the operational amplifier 121 in the non-energized state is corrected from a negative value to a small value on the positive side. As a result, it is possible to suppress deterioration in the phase current detection accuracy caused by the rise delay event without narrowing the controllable region more than necessary.

Next, an example of the operation of the offset correction section 130 will be described with reference to FIG. 7.

FIG. 7 is a schematic flowchart showing an example of the operation of the offset correction section 130.

First, the process in FIG. 7 enters a standby state ("NO" in step S700) in which the ignition switch is turned on. When the ignition switch is turned on (“YES” in step S700), a drive prohibition state is created to prohibit driving of the motor 6 of the electric oil pump 1 (step S702). In the drive prohibited state, the motor control unit 120 does not drive the motor 6. This creates a non-energized state. When the non-energized state is formed, it is determined whether the output value of the A/D converter 122 is smaller than 0V (step S704), and if the output value of the A/D converter 122 is smaller than 0V (step ("YES" in S704), the set value of the offset correction register is incremented by "1" from the current value k (step S706). Then, as a result of changing the set value of the offset correction register, it is determined whether the output value of the A/D converter 122 has become 0V or more (step S708), and the output value of the A/D converter 122 has become 0V or more. If so (“YES” in step S708), the current value k of the setting value of the offset correction register becomes the “correction target value of the offset correction register”, and the setting value of the offset correction register is updated to the current value k. (step S710). When the current value k is updated, a state in which the drive prohibited state is canceled (that is, a drive enabled state) is formed (step S718), and the process in FIG. 7 ends.

Further, if the output value of the A/D converter 122 does not become 0V or more as a result of changing the setting value of the offset correction register ("NO" in step S708), it is determined whether the termination condition is satisfied. (Step S712). The termination conditions are, for example, when a drive command (for example, from the ECU 2) for the motor 6 of the electric oil pump 1 is generated, or when the current value k of the offset correction register setting value is the maximum value (see "+ side MAX" in Fig. 5). ), etc. When the termination condition is satisfied (“YES” in step S712), a state in which the drive prohibited state is canceled (that is, a drive enabled state) is established (step S718), and the process in FIG. 7 ends. In this case, the process from step S702 may be restarted at the stage when the drive command related to the motor 6 of the electric oil pump 1 is completed. Note that when the current value k of the set value of the offset correction register reaches the maximum value and the termination condition is satisfied, information indicating an abnormality of the current sensor, etc. may be generated. On the other hand, if the termination condition is not satisfied (“NO” in step S712), the process is repeated from step S706. That is, the set value of the offset correction register is incremented by "1" from the current value k (step S706), and as a result of changing the set value of the offset correction register, the output value of the A/D converter 122 becomes 0V or more. If so (“YES” in step S708), the current value k of the setting value of the offset correction register becomes the “correction target value of the offset correction register”, and the setting value of the offset correction register is updated to the current value k. (Step S710).

Further, if the output value of the A/D converter 122 is 0V or more (“NO” in step S704), it is determined whether the output value of the A/D converter 122 is less than a predetermined threshold Th1 (step S714). The predetermined threshold value Th1 is a threshold value for detecting a state in which the output voltage of the operational amplifier 121 in a non-energized state is excessive even if it is on the positive side, and is a positive adaptive value. If the output value of the A/D converter 122 is less than the predetermined threshold Th1 (“YES” in step S714), it is determined that there is no need to update (correct) the set value of the offset correction register, and the drive prohibition state is established. A released state (that is, a drivable state) is formed (step S718), and the process of FIG. 7 ends. On the other hand, if the output value of the A/D converter 122 is equal to or greater than the predetermined threshold Th1, it is determined that the setting value of the offset correction register needs to be corrected, and the process proceeds to step S716. In this case, the set value of the offset correction register is changed from the current value k to the minimum value (see "- side MIN" in FIG. 6) (step S716), and the process starts from step S708.

According to the process shown in FIG. 7, each time the ignition switch is turned on, it is determined whether or not the output value of the A/D converter 122 is smaller than 0 V when the non-energized state is formed. Even if the input offset voltage of the operational amplifier 121 changes due to environmental changes such as temperature or temperature, the change can be handled. However, in a modified example, the process shown in FIG. 7 may be executed only once when the vehicle is shipped, or the execution timing may be determined based on other conditions (for example, conditions related to mileage or period). may be done.

Further, according to the process shown in FIG. 7, not only when the output value of the A/D converter 122 when the non-energized state is formed is smaller than 0V, but also when the output value of the A/D converter 122 when the non-energized state is formed is Even if it is equal to or higher than the predetermined threshold Th1, the setting value of the offset correction register is corrected to the "correction target value of the offset correction register", so that the operational amplifier 121 may Even if the input offset voltage of the operational amplifier 121 changes, the input voltage of the operational amplifier 121 can be optimized. However, in a modified example, step S714 and step S716 may be omitted.

Although each embodiment has been described in detail above, it is not limited to a specific embodiment, and various modifications and changes can be made within the scope of the claims. It is also possible to combine all or a plurality of the components of the embodiments described above.

<Additional notes>
Note that the following additional notes are further disclosed regarding the above embodiments.

[Additional note 1]
an amplifier (for example, an operational amplifier 121) electrically connected to both ends of a resistor through which a current to be detected flows;
an A/D converter (for example, A/D converter 122) that is electrically connected to the output side of the amplifier and converts the output of the amplifier into A/D and outputs the resultant signal;
An offset correction unit (for example, the offset correction unit 130 )and,
A motor current value detection device (for example, a microcomputer 12).

According to Appendix 1, when the output of the amplifier is less than 0 in the non-energized state, offset correction processing is executed to correct the input offset correction voltage of the amplifier. It is possible to reduce certain inconveniences (namely, the delay in the rise of the output voltage of the amplifier with respect to the rise of the phase current, which deteriorates the accuracy of detecting the phase current).

[Additional note 2]
The offset correction unit determines whether the output of the A/D converter is less than 0 in the non-energized state, and when determining that the output of the A/D converter is less than 0, The motor current value detection device according to supplementary note 1, wherein the offset correction process is executed by changing the value of an adjustment parameter for adjusting the input offset correction voltage.
According to Appendix 2, based on the output of the A/D converter in the de-energized state, it is determined whether the input of the amplifier in the de-energized state (and accordingly the output of the amplifier in the de-energized state) is less than 0. can. Further, by using the value of the adjustment parameter for adjusting the input offset correction voltage, it is possible to reduce the inconvenience when the input of the amplifier is less than 0 in the non-energized state.
[Additional note 3]
The offset correction unit changes the value of the adjustment parameter to a first value such that the output of the A/D converter slightly exceeds 0 in the non-energized state, the motor current value according to appendix 2. Detection device.
According to Appendix 3, it is possible to correct the state in which the output of the amplifier is less than 0 in the non-energized state to the state in which the output of the amplifier slightly exceeds 0 in the non-energized state.
[Additional note 4]
The offset correction unit searches for the first value by changing the value of the adjustment parameter so that the output of the A/D converter varies across 0, the motor current according to appendix 3. Value detection device.
According to Appendix 4, the first value can be efficiently searched for by changing the value of the adjustment parameter so that the output of the A/D converter varies across zero.
[Additional note 5]
The offset correction unit detects the motor current value according to appendix 4, wherein the value of the adjustment parameter is the first value when the output of the A/D converter crosses 0 and becomes positive. Device.
According to appendix 5, the value of the adjustment parameter can be set to the value closest to 0 among the values of the adjustment parameter such that the output of the A/D converter exceeds 0 in the non-energized state.
[Additional note 6]
The motor current value detection device according to any one of Supplementary Notes 1 to 5, wherein the current to be detected is a current related to an inverter for driving an electric oil pump motor.
According to appendix 6, the electric oil pump motor can be controlled in a relatively wide controllable range based on the output of the A/D converter.

1 Electric oil pump 3 Oil pan 4 Temperature sensor 5 Oil pump 6 Motor 7 Rotation angle detection section 8 Drive device 9 Power supply section 10 Inverter 11 Shunt resistor 12 Microcomputer 120 Motor control section 121 Operational amplifier 122 A/D converter 124 Current value acquisition section 130 Offset correction section

Claims (6)

an amplifier electrically connected to both ends of a resistor through which the current to be detected flows;
an A/D converter that is electrically connected to the output side of the amplifier and converts the output of the amplifier into A/D and outputs the A/D converter;
an offset correction unit that performs offset correction processing to correct an input offset correction voltage of the amplifier when the output of the amplifier is less than 0 in a non-energized state where the current to be detected is not flowing;
A motor current value detection device comprising: The offset correction unit determines whether the output of the A/D converter is less than 0 in the non-energized state, and when determining that the output of the A/D converter is less than 0, The motor current value detection device according to claim 1, wherein the offset correction process is executed by changing the value of an adjustment parameter for adjusting the input offset correction voltage. The motor current according to claim 2, wherein the offset correction unit changes the value of the adjustment parameter to a first value such that the output of the A/D converter slightly exceeds 0 in the non-energized state. Value detection device. The motor according to claim 3, wherein the offset correction unit searches for the first value by changing the value of the adjustment parameter so that the output of the A/D converter varies across 0. Current value detection device. The motor current value according to claim 3, wherein the offset correction unit sets the value of the adjustment parameter when the output of the A/D converter crosses 0 and becomes positive as the first value. Detection device. The motor current value detection device according to any one of claims 1 to 5, wherein the current to be detected is a current related to an inverter for driving an electric oil pump motor.

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